Implantable medical device with detachable battery compartment

ABSTRACT

An implantable medical electronic tissue stimulating device is formed of two hermetically sealed, fluid impervious housings, one containing an electronic pulse generator and the other a battery power supply. The two are adapted to be mechanically and electrically coupled together through a coupler/connector whereby current from the battery in one sealed housing is fed to the electronic pulse generator in the other sealed housing.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.10/643,369, filed Aug. 19, 2003, the specification of which is hereinincorporated by reference.

BACKGROUND OF THE INVENTION

I. Field of the Invention

This invention relates generally to implantable medical tissuestimulating devices, and more particularly to a hermetically sealedpulse generator with an independent, hermetically sealed batterycompartment.

II. Discussion of the Prior Art

Implantable pacemakers, cardiac defibrillators and neural stimulatorstypically comprise a single hermetically sealed case or housingcontaining a microprocessor and a pulse generator controlled by themicroprocessor for delivering tissue stimulating pulses at programmedtime intervals along with a battery power supply for supplyingelectrical current to the electronic circuitry. Given the complexity andcapabilities of present-day tissue stimulators, they may have amanufacturing cost approaching ranging between $1,000.00 and $3,000.00.

The battery power supply may typically comprise a lithium iodide cell inthat such batteries do not generate a gas during discharge that wouldmake the sealing of the implantable device problematic. Implantablemedical devices of the type described herein have a somewhat limitedshelf life and a substantial cost burden is incurred by themanufacturers of such devices in the event that sales do not deplete theinventory quickly enough. In that the battery and the somewhat expensiveelectronics are necessarily contained within a hermetically sealedcontainer or housing, the entire device must be scrapped if the unit isnot implanted within a period of 12 months of manufacture for certainmodules and 24 months for others. Taking into account the number ofdifferent models of pacemakers and AICDs manufacturers produce and theneed to maintain an inventory of each, losses due to scrapping caneasily reach several million dollars per year due to battery depletion.

During the test and burn-in phase of manufacture, the implantable deviceis subjected to elevated temperatures to stress the integrated circuitsand other components of the microprocessor-controlled pulse generator todetect hardware faults. The elevated temperatures are known to causebattery degradation.

Thus, a need exists for an implantable tissue stimulator that will havea fresh, fully charged battery at the time of implant irrespective ofthe date of manufacture. The present invention provides a solution.

SUMMARY OF THE INVENTION

The problems with the prior art design discussed above are resolved inaccordance with the present invention by providing an implantablemedical tissue stimulating device that comprises an electronic pulsegenerator contained in a first hermetically sealed housing member, abattery power supply contained in a second hermetically sealed housingmember and a means for mechanically and electrically coupling the firstand second housing members together at the time of implant whereby afresh battery begins to furnish energy to the electronic circuitry atthe time of implant rather than at the time of manufacture of the pulsegenerator.

DESCRIPTION OF THE DRAWINGS

The foregoing features, objects and advantages of the invention willbecome apparent to those skilled in the art from the following detaileddescription of a preferred embodiment, especially when considered inconjunction with the accompanying drawings in which like numerals in theseveral views refer to corresponding parts.

FIG. 1 is an isometric view of an implantable medical tissue stimulatorconstructed in accordance with the present invention where the batterycompartment and the pulse generator compartment are joined to oneanother;

FIG. 2 is an exploded view illustrating the parts comprising theelectronics compartment;

FIG. 3 is an exploded view showing the battery compartment disconnectedfrom the pulse generator compartment;

FIG. 4 is a perspective view similar to FIG. 2 but illustrating the malecoupling/connector portion incorporated into the battery compartment;and

FIG. 5 is an enlarged cross-sectional view taken through thecoupling/connector and seal mechanically and electrically joining thebattery compartment to the pulse generator compartment.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In FIG. 1 there is indicated generally by numeral 10 and implantablemedical tissue stimulating device, such as an implantable pacemaker, anautomatic implantable cardiac defibrillator or other type of tissuestimulator known in the art. It is seen to comprise a first hermeticallysealed housing or compartment 12 that is designed to contain theelectronic circuitry comprising a microprocessor-controlled pulsegenerator and a second hermetically sealed housing 13 for containing anelectrochemical cell or battery for powering the electronic circuitry.

As is shown in the exploded view of FIG. 2, the housing 12 is preferablyfabricated from a metal, such as titanium, and is comprised of twohalves 12 a and 12 b that are brought together and joined by weldingalong their mating edges 14 and 16. Before welding the two halvestogether, an electronic circuit module 18 is placed in the housing, asis a lead connector block assembly that comprises a metal shell 20having lead receiving bores as at 22 and 24 and a pocket into which isfitted a connector block 26. The connector block 26 is formed from aninsulating material and includes longitudinally extending bores that areadapted to receive the proximal terminal connectors on medical leads(not shown) that plug into the openings 22 and 24 of the shell 20.Fitted into the connector block 26 is a plurality of conductive leadlocking blocks 28, 29, 30 and 31 into which contact areas on theproximal terminal end of the medical lead are intended to mate. Theconnector block assembly includes a feedthrough member 32 that becomeswelded to the base of the shell 20 to provide rf isolation. First,however, conductive pins 34 on the feedthrough member 32 are welded tothe contact blocks 28-31 and to predetermined nodes on the electroniccircuit module 18. Insulating pads, as at 35 fit between the contactblocks and electrically isolate the contact blocks and feedthrough pinsfrom the shell 20.

Thus, when the housing halves 12 a and 12 b are brought together andwelded, the electronic circuitry, as well as the connector for theproximal terminal of medical leads, are hermetically sealed within thehousing. Also, a battery coupler/connector 36 is fitted intosemicircular sockets 38 formed in the two housing halves 12 a and 12 band welded in place. The positive and negative poles 40 of thecoupler/connector 36 are welded to appropriate tie points on theelectronic circuit 18 prior to placement of the surrounding housing 12.

Referring again to FIG. 1, the second hermetically sealed housing member13 contains a battery power supply that when appropriately coupled tothe housing member 12 provides the necessary energization for theelectronic circuit module 18.

As best seen in FIG. 2, the battery housing 13 includes a malecoupler/connector member 44 that is adapted to mate with the femalecoupler 36 forming part of the first housing 12 for the electronicscircuitry.

Referring next to FIG. 3, when the battery coupler/connector member 44is inserted into the coupling member 36 of the hermetically sealedelectronic circuit housing member 12 and then the battery housing 13 isrotated approximately 90° so that the battery housing and the circuithousing become aligned as in FIG. 1, the two housing halves becomepositively locked together. This is achieved by providing a helicalthread 46 of a predetermined pitch on the battery terminal 44 and thatmates with an internal thread formed in the female coupler 36.

Illustrated in FIG. 5 is a cross-sectional view taken through thebattery housing 13 showing the chemical cell 42 and through thecoupler/connector member 44 and the mating female coupler socket 36 toshow their internal construction. The socket 36 forms one conductor formating with a first battery terminal 45 while the center post 43 mateswith the second battery terminal 47. An insulating tube 48 surroundsbattery terminal 47 and electrically isolates it from the terminal 46.

Built into the above-described mechanism for removably coupling thefirst and second housing members to one another is an elastomeric seal49 preventing ingress of body fluids into the interface between the malebattery coupler/connector member 44 and the female coupler socket 36.

To prevent rotation of the battery housing 13 relative to the circuithousing 12 once the coupler members 36 and 44 are joined, a springbiased latch 50 projects from a side surface 52 of the battery housing13 as shown in FIGS. 3 and 4. The latch 50 is designed to fit into anassociated groove (not shown) formed midway across the width dimensionof the projecting portion 54 of the housing 12. If it becomes necessaryto uncouple the battery from the electronics portion of the implantabledevice, a suitable needle probe 55 (FIG. 1) may be inserted into thegroove at its entrance point 56 whereby the barb of latch 50 can bedepressed so as to no longer reside in the groove, at which point thebattery housing 13 can be rotated to uncouple the threaded connectionbetween the two coupler/connector members 36 and 44.

Thus, it can be seen that a secure mechanical and electrical connectioncan be established between the battery supply 42 contained within thehousing member 13 and the electronic circuitry contained within thehousing member 12 such that the necessary operating voltages becomeavailable to the electronic circuitry. Since this connection can be madeat the time of implant, it is assured that the battery will be fresh andneed not have been subjected to the elevated temperatures used duringthe test and burn-in phase of manufacture of the device.

This invention has been described herein in considerable detail in orderto comply with the patent statutes and to provide those skilled in theart with the information needed to apply the novel principles and toconstruct and use such specialized components as are required. However,it is to be understood that the invention can be carried out byspecifically different equipment and devices, and that variousmodifications, both as to the equipment and operating procedures, can beaccomplished without departing from the scope of the invention itself.

1. An implantable medical device, comprising: a first hermeticallysealed housing containing electronic circuitry and including a firstthreaded connector; and a second hermetically sealed housing containinga battery and including a second threaded connector configured to matethe first threaded connector, wherein the first and second hermeticallysealed housings are configured to be connected to each other by matingthe first and second threaded connectors, including rotating the secondhermetically sealed housing relative to the first hermetically sealedhousing, such that the electronic circuitry is energized by the battery.2. The implantable medical device of claim 1, wherein the electroniccircuitry comprises a pulse generator.
 3. The implantable medical deviceof claim 1, wherein the first and second hermetically sealed housingsare removably connected to each other.
 4. The implantable medical deviceof claim 3, wherein the first threaded connector is an internallythreaded female connector, and the second threaded connector is anexternally threaded male connector.
 5. The implantable medical device ofclaim 4, wherein the first and second hermetically sealed housings arealigned and locked together by rotating the second hermetically sealedhousing approximately 90 degrees.
 6. The implantable medical device ofclaim 4, comprising a spring biased latch projecting from the secondhermetically sealed housing and configured to prevent rotation of thesecond hermetically sealed housing relative to the first hermeticallysealed housing after the first and second hermetically sealed housingsare connected.
 7. The implantable medical device of claim 1, wherein thefirst hermetically sealed housing and the second hermetically sealedhousing are each fabricated from a metal.
 8. An implantable medicaldevice, comprising: a first hermetically sealed housing containing anelectronic pulse generator and including a threaded female connector;and a second hermetically sealed housing containing a battery andincluding a threaded male connector configured to mate the threadedfemale connector, wherein the first and second hermetically sealedhousings are configured to be aligned and locked together by insertingthe threaded male connector into the threaded female connector androtating the second hermetically sealed housing relative to the firsthermetically sealed housing.
 9. The implantable medical device of claim8, wherein the first and second hermetically sealed housings areremovably connected by inserting the threaded male connector into thethreaded female connector and rotating the second hermetically sealedhousing relative to the first hermetically sealed housing.
 10. Theimplantable medical device of claim 9, wherein the first and secondhermetically sealed housing are aligned and locked together by rotatingthe second hermetically sealed housing approximately 90 degrees.
 11. Theimplantable medical device of claim 9, comprising a pacemaker.
 12. Theimplantable medical device of claim 9, comprising a defibrillator.
 13. Amethod for making an implantable medical device, the method comprising:providing a first hermetically sealed housing; incorporating a firstthreaded connector into the first hermetically sealed housing; providinga second hermetically sealed housing; incorporating a second threadedconnector into the second hermetically sealed housing, the secondthreaded connector configured to mate the first threaded connector suchthat the first and second hermetically sealed housing are aligned andlocked by rotating the second hermetically sealed housing relative tothe first hermetically sealed housing; and placing electronic circuitryin one of the first and second hermetically sealed housings.
 14. Themethod of claim 13, wherein providing the first hermetically sealedhousing comprises providing two housing halves each including asemicircular socket, and incorporating the first threaded connector intothe first hermetically sealed housing comprises fitting the firstthreaded connector into the semicircular sockets.
 15. The method ofclaim 14, comprising: placing an electronic pulse generator in the firsthermetically sealed housing; and welding the two housing halvestogether.
 16. The method of claim 13, wherein incorporating the firstthreaded connector into the first hermetically sealed housing comprisesincorporating a female connector into the first hermetically sealedhousing, and incorporating the second threaded connector into the secondhermetically sealed housing comprises incorporating a male connectorinto the second hermetically sealed housing.
 17. The method of claim 13,wherein providing the first and second hermetically sealed housings eachcomprise providing a metal housing.
 18. The method of claim 17, whereinplacing the electronic circuitry in one of the first and secondhermetically sealed housings comprises placing an electronic pulsegenerator in the first hermetically sealed housing, and comprisingplacing a battery in the second hermetically sealed housing to energizethe electronic pulse generator.
 19. The method of claim 13, comprising:forming a groove on the first hermetically sealed housing; andincorporating a spring biased latch projecting from the secondhermetically sealed housing, the spring biased latch configured to fitinto the groove.
 20. The method of claim 19, comprising: inserting thesecond threaded connector into the first threaded connector; androtating the second hermetically sealed housing relative to the firsthermetically sealed housing.